Food, specific dietary components, and fluid volumes with which a drug is ingested have been shown to influence the rate and extent of drug absorption after oral administration. Although it is generally considered that food delays and reduces drug absorption, this is not always the case. Studies carried out in the laboratory show that the rate of absorption of orally dosed theophylline and propoxyphene is significantly reduced by food but overall absorption efficiency is not significantly affected. In this proposal the influence of food, specific dietary components and ingested fluid volumes on the absorption of several acidic and basic drugs will be examined in healthy human volunteers. Drugs to be examined include warfarin, erythromycin stearate, erythromycin estolate, ampicillin, amoxicillin, tetraacycline, doxycycline, aspirin, griseofulvin, trimethoprim and sulfamethoxazole. Drugs will be administered as single doses to six subjects as a crossover study. Drugs will be dosed immediately following standardized high fat, high protein and high cargohydrate meals and also to fasted subjects together with varying water volumes. Relative bioavailability due to treatments will be calculated from pharmacokinetic treatment of plasma levels during appropriate time periods after dosing. BIBLIOGRAPHIC REFERENCES: P. G. Welling, L.L. Lyons, W.A. Craig and G.A. Trochta: Influence of diet and fluid on vioavailibility of theophylline. Clin. Pharm. Therap., 17: 475-480, 1975. P. G. Welling, L. L. Lyons, F. L. S. Tse and W. A. Craig: Plasma levels of propoxyphene: Influence of diet and fluid. Submitted to Clin. Pharm. Therap., 1975.